The Developmental Genomics Section has been using a combination of zebrafish genetics and molecular embryology to study ear development and hearing regeneration. Two of mutations are being actively studied. The first is a mutation is in the zebrafish ortholog of the mouse gene Oct4. This gene is essential for maintaining stem cell pluripotency. We have performed transcriptional profiling in mouse ES cells and zebrafish embryos after modulating Oct4 levels. The second mutation affects the regenerative ability in several tissues of the zebrafish embryo including the hair cells of the inner ear. We are cloning the transcript and establishing the subcellular localization of the protein and determining the function for the protein. [unreadable] We have initiated research on hair cell regeneration in adult zebrafish. We are exposing zebrafish to sound at high enough decibles to cause damage. We will then profile the transcriptional program that is initiated during regeneration of the hair cells. [unreadable] Another focus of the lab is to develop tools for studying gene expression on a genome wide scale. We have developed a technique for rapidly mapping the integration sites for retroviruses and transposable elements and we are now in the second phase of a process to map thousands of proviral integrations in the zebrafish germline to create an archived zebrafish mutant resource. We are approximately half way through the first phase to map 1600 retroviral integrations and test the efficacy of mutagenesis. This phase will establish the framework for generating the resource and determine the number of total fish necessary to map 100,000 retroviral integrations which will disrupt an estimated 12,000 genes.